Process of making molded articles from urea or its derivatives, solid polymeric aldehydes, and filling bodies



Patented Apr. 2, 1935 PROCESS OF -MAKING MOLDED ARTICLES FROM UREA ORITS DERIVATIVES, SOLID POLYMERIC ALDEHYDES, AND FILLING BODIES OttoSiisscnguth, Erkner, near Berlin, Germany, assignor, by mesneassignments, to Bakelite Corporation, New York, N. Y., a corporation ofDelaware -No -Drawing. Application January 23, 1929,- Serial No.334,601. In GermanyFebruary 4 Claims.

Numerous processes for the purpose of making condensation products fromurea and formaldehyde have already been proposed.

According to those well known processes the condensation of urea andformaldehyde is effected in an aqueous solution and in order to producethe pure resin, a long and diflicult distillation process is necessary..The resinsobtained are thereafter hardened in molding forms or mixedwith filling bodies and subjected to hotpress molding.

According to my invention it is possible to manufacture molded articlesfrom urea and formaldehyde in a much simpler and more perfect way bycondensing the componentsin the absence of solvents in a dry state asdescribed here,- after, that is to say by employing solid polymericaldehydes instead of the usual aldehyde solutions. In view of thesimplification of the equipment and of considerable saving of time thepresent process offers great economical and technical advantages.

According to my invention urea, paraformaldehyde and suitable fillingbodies of organic or inorganic nature, for instance cellulose and itsderivatives, wood flour, asbestos, kaolin, graphite are thoroughlyground, for example in a ball mill or in another appropriate deviceuntil a homoeneous mixture is 'obtained. The urea can be,

mixed with the filling bodies and then with paraformaldehyde, or thefilling bodies can be added to the mixture of paraformaldehyde and urea,or

' bodies, for instance certain kinds of paper, asbestos and lithopone,it is possible to obtain articles which are of a pure white colour andfast to light. The mixture may also be subjected to coldpressing-thereafterheatin the articles to temperatures of 100-120degrees C. The cold pressed articles are heated at a temperature of100-120 degrees for instance for two to five hours,

The resulting If fibrous substances are to be incorporated into themixture, then the components must be mixed preferably hot in a kneadingmachine or on mixing rolls or in other suitable devices. For instance amixture of ureaand pa'raformaldehyde is made in the proportionsindicated hereafter. This mixture of urea and paraformaldehyde begins tomelt already at a temperature of -70 degrees C. and penetrates thefibrous substances completely. The hot mixture must be kneaded until asubstance is obtained which is brittle when cooled and which may then beground and subjected to hot-press molding.

The mechanical and chemical resistance of the molded articles obtainedaccording to my invention may vary byadding suitable admixtures to thepress mixture of urea, paraformaldehyde and filling bodies. resins, forinstance colophony, copal, artificial resins capable or not capable ofhardening, for instance condensation products from phenols andaldehydes, phthalic acid, glyceric ester, or

Such admixtures may be natural substances capable of binding freeformaldehyde as for instance phenol, p-toluolsulfamide, amines andsubstances binding the water which is formed during the condensation ofresin, such as gypsum, cement etc. Several of these substances may bemixed witheach other and then added to the molding mixture.

Example 1 A mixture of Parts by weight Urea Paraformaldehyde 100 Lithop250 is ground in a ball mill until a complete homogeneous mixture isobtained. The mixture may be pressed, for instance at C. or at 1802C aremixed in the heat in a'kneading machine until a mass is obtained whichis brittle when cooled and which is then ground and subjected to hotpress'molding as indicated in Example 1.

l zample'ti j Parts by weight Urea 100 ehyde 100' p-toluolsuli'amide 20calcined gypsum 100 Lithopone' 100 Paper pu p 50 are ground in a ballmill and molded under hot Dress conditions as described in Example -1.

Instead of urea, derivatives of the same, for instance thin-urea,acetyl-urea, maybe used, and other suitable solid aldehydes, forinstance trioxymethylene, poloxymethylene, may replace theparaiormaldehyde, and the term urea compolmd and solid aldehydes" areapplied herein to all these compositions. The invention is notrestricted to theiapplication of urea and paraiormaldehyde, and likewiseit is not restricted to the indicated special proportions and to thedescribed special procedures of mixing, molding etc. The expressionfilling bodies is used herein to include also colouring and plasticizingagents or the other usual admixtures.

I claim: I v 1. Process of making a molded article which comprisescommingling'in the dry solid state a urea compound, a solid polymericaldehyde and a filler, and then hot molding the mixture to cause a resincondensation and the hardening of the resulting resin simultaneouslywith the formation of the article. 1

2. Process of making a molded article as defined in claim 1 in which thefiller-is of a basic

